I think that people are too quick to say that Ellen White wasn't using "exegesis" when she made so-called "homiletical" statements.
For example, in the Desire of Ages, Ellen White, in describing Christ, calls Him "the Chiefest among ten thousand" and the One "altogether lovely" (p. 827). These titles are taken from Song of Solomon 5 and would seem to have no messianic reference at all. The passage is an interplay between two young people who are head-over-heals for each other.
However, if one carefully (and exegetically) studies Song of Solomon 5, they would notice something very interesting. In describing her lover, the Shulamite uses an overwhelming number of words that parallel the description of the sanctuary/temple. Scholars have recognized that this isn't simply a haphazard connection. There is something deeper going on. One commentator says that "we resist using this fact to allegorize the text, but again we suggest that it associates her description with something exalted, even holy" (Tremper Longman III, Song of Solomon , NICOT, p. 174).
In my personal study of this book, I would say that there is definitely a typological interpretation that can be pursued. It's not allegorical or even prophetic, but there is exegetical ground to stand on to believe that there are messianic fulfillments. Ellen White, the few times she does refer to the book, isn't simply neglecting exegesis. Maybe she sees things exegetically that we have failed to thusfar.
The same can be said for the New Testament prophets and writers (cf. Matthew 1:23, etc.). Just because our "exegesis" of Old Testament passages may not draw the same conclusions, it doesn't mean the New Testamemt writers weren't using exegesis, or were using poor exegesis.
For many years, Ellen White's views on health didn't allign with "enlightened" science, but time has shown that her interpretations are/were correct. Perhaps our exegesis will show the same as time goes on.